Evaluation of deltamethrin-loaded Zn-Fe, Zn-Al-GA layered double hydroxide, and Fe-O nanoparticles against resistant Rhipicephalus annulatus ticks.

The over use of deltamethrin has resulted in the development of resistance. Thus, the search for a new method to improve its acaricidal effect is the target of the present study. Layered double hydroxide (LDH) compounds are now used as drug delivery systems. Deltamethrin (Butox®) was loaded on Zn-Fe LDH, Zn-Al-GA layered double hydroxide (LDH), and Fe-oxide nanoparticles NPs. Then its acaricidal efficacy was evaluated. The nanocomposites (NCs) were prepared by the co-precipitation method and characterized before and after deltamethrin loading. The deltamethrin-loaded NCs were applied against the phenotypically resistant Rhipicephalus annulatus tick (adult and larvae). The adult ticks treated by Butox® alone or Butox® loaded nanocomposites at different concentrations showed no mortality. A significant (P≤0.05) reduction in egg production index was observed at the recommended dose (X) (1 μl/ml distilled water) and its bi-folds (2X, 3X, and 4X) in ticks treated with deltamethrin/Zn-Fe LDH nanocomposites compared to deltamethrin alone. Moreover, no significant difference (P>0.05) was recorded in larval mortality between the treatments with deltamethrin alone and its loaded nanocomposites. Also, the nanomaterials alone without conjugation with deltamethrin revealed a low mortality rate. Deltamethrin-loaded nanocomposites even improve effect against adult tick but cannot overcome tick resistance to deltamethrin that needs more search. The acaricidal activity of deltamethrin was not improved after loading it with these nanocomposites.